Conventionally, an art is known in which a working vehicle such as a backhoe loader has a PTO hydraulic port for supplying pressure oil to a hydraulic actuator of an external hydraulic apparatus such as a breaker or a grapple, and for supply and discharge of pressure oil to the PTO hydraulic port, an electromagnetic type selector valve with an electromagnetic solenoid is employed such as an electromagnetic selector valve in which a spool in the selector valve is moved directly by an electromagnetic solenoid so as to change the route of pressure oil or an electromagnetic hydraulic selector valve in which an electromagnetic pilot valve having an electromagnetic solenoid is actuated and a main spool is moved indirectly by hydraulic pressure from the electromagnetic pilot valve so as to change the route of pressure oil (for example, see the Patent Literature 1).
On the other hand, such an electromagnetic type selector valve requires complex oil paths and control construction, and the large valve is employed so as to drive directly an external hydraulic apparatus. Therefore, when large numbers of the valves are employed, the cost of parts is increased. Accordingly, art of a mechanical selector valve is also known in which the spool of the selector valve is moved mechanically by manual power transmitted through a pedal, a lever or the like (for example, see the Patent Literature 2).    Patent Literature 1: the Japanese Patent Laid Open Gazette 2007-92763    Patent Literature 2: the Japanese Patent Laid Open Gazette 2003-176549